Much attention has been given to the toxicologic effects of plasticizers to which patients may be exposed via components of dialysis equipment, plastic tubing and plastic blood bags. Although numerous toxicologic studies have been able to demonstrate effects only after massive doses, concern persists that these compounds may be deleterious. Consequently, suggestions have been made to limit the plasticizer exposure of patients by removing it from contact with body or parenteral fluids wherever possible. To document the specific effect of the common plasticizer DEHP on red cells, this study was designed to investigate changes occurring in the red cell membrane in the presence and absence of DEHP in stored blood. Significance of these changes will be evaluated through 51chromium survival studies of autologous red cells stored in the presence or absence of DEHP.